The term "titration" is understood to mean the determination of the unknown content of an aqueous solution of an acid or base (the sample) by the addition of a base or acid solution (the reagent) of known concentration until an indicator undergoes a change in color. From the number of cubic centimeters and concentration (titer) of the base or acid consumed, the acid or base content of the solution titrated in this manner can then be readily calculated.
For titration under laboratory conditions, the known discontinuous titration procedure with pipettes and (optionally motor-driven) burettes is used. Since this procedure requires the constant presence of an operator, it is unsuitable for industrial use.
It has already been proposed to automate the discontinuous titration in order that it can also be used industrially. However, since considerable problems arise during the delivery of the sample and the reagent to the titration vessel, during the draining of the titrated solution from the titration vessel, and during the metering of the quantities of liquid, which, among other things, requires a large number of valves, this automated discontinuous titration has not gained acceptance. In addition, controls, which are expensive because of the valves, are necessary and the calculated titer must be stored from one titration to the next, for which additional devices are required.
Continuous titration procedures for industrial use are known, in which sample and reagent are fed into the titration vessel in a controlled and variable ratio. To do this, at least two adjustable pumps are necessary, the control of which requires expensive servo systems and which, in addition, consume a large amount of power.